HEP-Astro Seminar | Searching for New Physics in the Late Universe With Millions of Galaxies in Millions of Dimensions

The growth of cosmic structures provides a bridge between observations and theories. In the first part of this talk, I will review the sigma8 tension between early- and late-time measurements of cosmic structure growth, and its physical implications. Are we seeing a chink in the standard cosmological model’s armor? To fully unveil the origin of this tension (and possibly new physics in the late Universe), galaxy clustering and spectroscopic surveys like DESI will play an indispensable role. In the second part of the talk, I will introduce a novel framework to extract cosmological information from millions of galaxies in spectroscopic surveys, directly at the field level-i.e. the three-dimensional map level with millions of grid points. The ultimate goal is to achieve a percent-level constraint on sigma8 and growth of structure. I will discuss recent progress towards this goal, highlighting latest breakthroughs, results in a community data challenge, and remaining challenges.